1. Field of the Invention
The present invention relates generally to a magnetic head, and more particularly, to a magnetic head for recording and reproducing data in a state in which the magnetic head floats over a rotating recording medium, that is, a rotating magnetic disk, due to a change in air flow arising between the magnetic head and the magnetic disk.
2. Description of the Related Art
Generally, an ordinary magnetic disk drive that uses a flexible magnetic disk having a coercive force of 900 oersted (Oe) or less as a magnetic recording medium allows a relatively low rotational speed of for example 300 rpm in this case, magnetic recording and reproduction is performed by causing the magnetic bead to be in direct sliding contact with the magnetic disk.
However, with advances in recent years in high-density recording on magnetic disks, the rotation speed of the magnetic disk has been increased to for example 3000 rpm, with the coercive force of the magnetic disk being increased to 1500 Oe or more. As a result, in order to accommodate such so-called high-capacity magnetic disks a magnetic disk drive has appeared in which the magnetic head is provided with a narrow gap. Hereinafter such a magnetic disk drive will be referred to as a high-capacity magnetic disk drive.
Since a high-capacity magnetic disk drive allows the magnetic disk to be rotated at high speeds, the magnetic disk and the magnetic head used therein may be easily damaged if the magnetic head were to be caused to be in direct contact with the magnetic disk, as is done in the conventional magnetic disk drive.
As a result, the high-capacity magnetic disk drive is designed so that the magnetic head floats in an elevated state over the surface of the high-capacity magnetic disk due to an elevating force arising as a result of a change in an air flow caused by a relative speed between a slider surface of the magnetic head and the magnetic disk. Magnetic recording and reproduction is performed while a state of non-contact between the magnetic head and the magnetic disk is maintained.
FIGS. 1, 2, 3, 4 and 5 show a magnetic head used in the conventional high-capacity magnetic disk drive. As shown in FIGS. 1 and 2, the conventional high-capacity magnetic head 1 generally comprises a slider 2 and a magnetic head unit 3 The slider 2 supports the magnetic head unit 3 and causes the magnetic head unit 3 to float over the magnetic disk 6.
The top surface of the slider 2 forms an air bearing surface for forming an air bearing with respect to the magnetic disk 6. Additionally, a central groove 2a is formed at a central position of the top surface of the slider 2. As shown in FIG. 1, the central groove 2a divides the air bearing surface into a first air bearing surface 2b located to the right side of the central groove 2a and a second air bearing surface 5 located to the left side.
The magnetic head magnetic head unit 3 and a pair of grooves or slots 4 are provided at the first air bearing surface 2b. The magnetic head unit 3 for performing magnetic recording and reproducing is formed by sandwiching a gap member between thin plates of magnetic cores.
The slots 4 extend in a tangential direction of the magnetic disk 6, that is, in the direction of arrow X in FIG. 1, and provide a vent for an air flow produced between the magnetic disk 6 and the first air bearing surface 2b. By providing a vent to the air flow produced between the magnetic disk 6 and the first air bearing surface 2b, an elevating force exerted on the magnetic head 1 is reduced. Accordingly, by providing the slots 4, the elevating force of the magnetic head 1 can be controlled.
As described above, the second air bearing surface 5 is formed to the left of the central groove 2a located on the top surface of the slider 2 as shown in FIG. 2. Like the first air bearing surface 2b, the second air bearing surface 5 also produces a force for elevating the magnetic head 1.
FIG. 3 is a lateral cross-sectional view from a radial direction of disk approach. As shown in the drawing, a pair of magnetic heads are supported so as to be opposite each other within the magnetic disk drive. The elevating force generated by the second air bearing surface 5 described above exerts a force that pushes the magnetic disk 6 in the direction of the first air bearing surface 2b, that is, in the direction of the magnetic head unit 3, of the opposite magnetic head 1. Accordingly, the second air bearing surface 5 also functions as a pressure pad for pressing the magnetic disk 6 toward the opposite magnetic head 1.
Additionally, as described above slots 4 are formed in the first air bearing surface 2b. The slots 4 provide a vent for the air flow produced between the magnetic disk 6 and the first air bearing surface 2b, thus reducing the elevating force exerted on the magnetic head 1. Accordingly, the magnetic disk 6 is deformed by a negative pressure generated in the slots 4 and a pressure generated at the second air bearing surface 5 due to a change in air flow so as to warp toward a gap 3a as the magnetic disk 6 rotates between the pair of magnetic heads 1. With this construction, optimum recording to and reproduction from the magnetic disk 6 is ensured even with floating magnetic heads 1 A description will now be given of how the magnetic heads 1 face the magnetic disk 6, with reference to FIG. 4 and FIG. 5. FIGS. 4 and 5 show views of a state in which the magnetic head 1 is recording to or reproducing from a magnetic disk 6, from a radial Y direction of the magnetic disk 6.
FIG. 4 shows the magnetic disk 6 in a state of optimal approach to the magnetic head 1.
As shown in FIG. 4, a pair of slots 4 are formed in the first air bearing surface 2b in which the first magnetic head unit 3 is provided. These slots 4 are formed along an entire length of the first air bearing surface, that is, a direction indicated in the drawing by the double-headed arrow X, from a leading edge 7 of the magnetic head 1, that is, an edge side of the magnetic head 1 at which the magnetic disk 6 enters the magnetic head 1, to a trailing edge 8 of the magnetic head 1, that is, an edge side of the magnetic head 1 at which the magnetic disk 6 exits the magnetic head 1. As a result, a reduction in the elevating force due to the presence of the slots 4 is generated over the entire extent of the length of the first air bearing surface 2b. 
Accordingly, even in a state of optimal approach a distance H between the magnetic disk 6 and the leading edge 7 of the magnetic head 1 in the above-described construction in which the slots 4 are provided is smaller than a corresponding distance in a construction in which the slots 4 are not provided.
Moreover, with such a construction the magnetic disk 6 is maintained in close proximity to the magnetic head unit 3 as a result of the reduction in elevating force by the slots 4, thus providing optimal magnetic recording and reproduction.
By contrast, FIG. 5 shows a state in which the magnetic disk 6 approaches the magnetic head 1 at a height position lower than that of an optimal approach. Such a small-clearance state of approach results from the flexibility of the magnetic disk 6 or from inevitable errors in the production process thereof.
When the height of the magnetic disk 6 upon approach to the magnetic head 1 is lower than a standard optimum height position as described above, the distance H is reduced to such an extent that the magnetic disk 6 may come into contact with the leading edge 7 of the magnetic head 1, and the magnetic disk 6 or the leading edge 7 of the magnetic head 1 may be damaged as a result.
At the same time, although the magnetic disk 6 is ordinarily enclosed in a hard case so as to prevent particles of dirt and dust from adhering to the surface of the magnetic disk 6, it is impossible to completely prevent the attachment of dust thereto, with the result that, inevitably, dust collects on the surface of the magnetic disk 6. If magnetic recording to and reproducing from a magnetic disk 6 to the surface of which dust has adhered is performed using a magnetic head 1, the dust may break loose from the surface of the magnetic disk 6 by the air flow generated at the first and second air bearing surfaces 2b, 5 and adhere to the magnetic heads 1.
As a result, because the width dimension of the slots 4 in the conventional magnetic head 1 is small the flow of air is restricted and thus dust accumulates in the slots 4. If this accumulated dust then breaks loose from the first and second air bearing surfaces 2b, 5, the magnetic disk 6, which is rotating at high speed, may be damaged by collision with the dust or the flow of air may be impaired by the dust, thus impairing proper magnetic recording and reproduction.
Accordingly, it is a general object of the present invention to provide an improved and useful magnetic head in which the disadvantages described above are eliminated. A more specific object of the present invention is to provide a magnetic head capable of reliably preventing contact between the slider and the recording medium while maintaining a state of optimum magnetic recording and reproduction by preventing the adherence of dust.
The above-described objects of the present invention are achieved by a magnetic head comprising:
a first magnetic head unit for recording to and reproducing from a first flexible rotating recording medium.
a second magnetic head unit for recording to and reproducing from a second flexible rotating recording medium having a coercive force lower than a coercive force of the first flexible rotating recording medium;
a slider supporting the first magnetic head unit, the slider having a central groove separating a first air bearing surface at which the first magnetic head unit is provided and a second air bearing surface at which the second magnetic head unit is provided, the slider generating an elevating force from an a flow generated in a space between the first and second air bearing surfaces and the flexible rotating recording media;
the first air bearing surface having a width dimension A1 located on a leading edge side of the magnetic head and substantially perpendicular to a direction from which the first or second flexible rotating recording medium approaches the magnetic head, and a width dimension A2 located on a trailing edge side thereof and substantially perpendicular to said direction, the width dimension A1 being larger than the width dimension A2; and
an elevating force control slot formed on at least the first air bearing surface so as to extend in a direction substantially perpendicular to the direction from which the first or second flexible rotating recording medium approaches the magnetic head, the elevating force control slot having an inside depth D1 and an outside depth D2 greater than the inside depth D1.
According to the invention described above, by making the width dimension A1 larger than the width dimension A2, contact between the leading side edge of the slider and the magnetic disk can be prevented and, further, the first magnetic head unit and the recording medium can be brought into close proximity to each other.
Additionally, by forming the elevating force control slot on at least the first air bearing surface so as to extend in a direction substantially perpendicular to the direction from which the first or second flexible rotating recording medium approaches the magnetic head, the elevating force can be reduced because the air flow arising between the bearing surface and the recording medium can be vented via the elevating force control slot.
Additionally, by making the outside depth D2 greater than the inside depth D1, the air flow generated at the slider flows from inside the elevating force control slot to outside the elevating force control slot. Therefore, dust that has broken loose from the recording media is transported from the inside to the outside via the air flow inside the elevating force control slot, that is, is exhausted to the outside of the magnetic head. As a result, adherence of dust to the magnetic head can be prevented, and further, damage to the recording media can be prevented. At the same time, optimum magnetic recording and reproduction can be maintained.
Further, by adjusting the internal and external depths D1 and D2, respectively, the speed with which air flows through the interior of the elevating force control slot can be controlled, and it is possible to easily set the air flow to a speed that provides optimal elevating force and dust exhaust.
Additionally, the above-described objects of the present invention are also achieved by the magnetic head as described above, wherein a bottom surface of the elevating force control slot is a slanting surface Additionally, the above-described objects of the present invention are also achieved by the magnetic head as described above, wherein at least one step portion is formed on the bottom surface of the elevating force control slot.
According to the inventions described above, the flow of air inside the elevating force control slot from the inside to the outside can be made smooth, and thus the adherence of dust to the magnetic heads can be more effectively prevented.
Additionally,the above-described objects of the present invention are also achieved by the magnetic head as described above, herein a portion of the central groove in the vicinity of the first magnetic head penetrates in a direction of a height of the slider.
According to the invention described above, the volume of air flow can be increased because air flows along a rear surface of the slider as well as the sides of the slider. Accordingly, reduction of the elevating force with respect to the recording medium and the exhaust of dust can be performed more effectively.
Additionally, the above-described objects of the present invention are also achieved by a magnetic head comprising:
a first magnetic head unit for recording to and reproducing from a first flexible rotating recording medium;
a second magnetic head unit for recording to and reproducing from a second flexible rotating recording medium having a coercive force lower than a coercive force of the first flexible rotating recording medium;
a slider supporting the first magnetic head unit, the slider having a central groove separating a first air bearing surface at which the first magnetic head unit is provided and a second air bearing surface at which the second magnetic head unit is provided, the slider generating an elevating force from air currents generated in a space between the first and second air bearing surfaces and the flexible rotating recording media;
the first air bearing surface having a width dimension A1 located on a leading edge side of the first magnetic head and substantially perpendicular to a direction from which the first or second flexible rotating recording medium approaches the magnetic head, and a width dimension A2 located on a trailing edge side thereof and substantially perpendicular to said direction, the width dimension A1 being larger than the width dimension A2; and
an elevating force control slot formed on at least the first air bearing surface so as to extend in a direction perpendicular to the direction from which the first or second flexible rotating recording medium approaches the magnetic head and at the same time penetrate in a direction of the height of the slider.
According to the invention described above, by making the width dimension A1 greater than the width dimension A2, contact between the leading side edge of the slider and, further, the first magnetic head unit and the recording medium can be brought into close proximity to each other.
Additionally, by forming the elevating force control slot on at least the first air bearing surface so as to extend in a direction substantially perpendicular to the direction from which the first or second flexible rotating recording medium approaches the magnetic head, the elevating force can be reduced because the air flow arising between the bearing surface and the recording medium can be vented via the elevating force control slot. Thus it is possible to control the elevating force for each bearing surface.
Additionally, by forming the elevating force control slot formed on at least the first air bearing surface so as to extend in a direction perpendicular to the direction from which the first or second flexible rotating recording medium approaches the magnetic head and at the same time penetrate in a direction of the height of the slider, the volume of air flow can be increased because air flows through the elevating force control slot along a back space and both sides of the slider. Accordingly, reduction of the elevating force with respect to the recording medium and the exhaust of dust can be performed more effectively.
Additionally, the above-described objects of the present invention are also achieved by the magnetic head as described above, wherein a depth of the central groove gradually increases as the central groove extends from a formation position of the elevating force control slot toward a trailing edge side of the first or second magnetic heads.
According to the invention described above, the flow of air inside the central groove flows easily from the position at which the elevating force control slot is formed toward the trailing edge side. Thus, dust that has broken loose from the recording media is exhausted from the magnetic heads toward the trailing edge by this flow of air flowing inside the central groove. As a result, the adherence of dust to the magnetic head can be prevented, and further, damage to the recording media can be prevented at the same time as optimum magnetic recording and reproduction can be maintained.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.